Method, apparatus and computer product for substrate processing

ABSTRACT

A method, apparatus and computer product for processing of substrates in at least a part of a substrate processing system is provided. In an embodiment, the method includes obtaining, using a processing unit, at least one of a rate of processing and a time of processing of a plurality of substrate lots to be introduced into a part of the substrate processing system and determining, using the processing unit, an order of introduction of the plurality of substrate lots into the part of the substrate processing system to at least one of increase the rate of processing and decrease the time of processing of the plurality of substrate lots.

FIELD

The present invention relates to processing of substrates in a substrateprocessing system.

BACKGROUND

The term “patterning device” as here employed should be broadlyinterpreted as referring to means that can be used to endow an incomingradiation beam with a patterned cross-section, corresponding to apattern that is to be created in a target portion of the substrate; theterm “light valve” can also be used in this context. Generally, the saidpattern will correspond to a particular functional layer in a devicebeing created in the target portion, such as an integrated circuit orother device (see below). Examples of such patterning devices include:

-   -   A mask. The concept of a mask is well known in lithography, and        it includes mask types such as binary, alternating phase-shift,        and attenuated phase-shift, as well as various hybrid mask        types. Placement of such a mask in the radiation beam causes        selective transmission (in the case of a transmissive mask) or        reflection (in the case of a reflective mask) of the radiation        impinging on the mask, according to the pattern on the mask. In        the case of a mask, the support structure will generally be a        mask table, which ensures that the mask can be held at a desired        position in the incoming radiation beam, and that it can be        moved relative to the beam if so desired;    -   A programmable mirror array. One example of such a device is a        matrix-addressable surface having a viscoelastic control layer        and a reflective surface. The basic principle behind such an        apparatus is that (for example) addressed areas of the        reflective surface reflect incident light as diffracted light,        whereas unaddressed areas reflect incident light as undiffracted        light. Using an appropriate filter, the said undiffracted light        can be filtered out of the reflected beam, leaving only the        diffracted light behind; in this manner, the beam becomes        patterned according to the addressing pattern of the        matrix-addressable surface. An alternative embodiment of a        programmable mirror array employs a matrix arrangement of tiny        mirrors, each of which can be individually tilted about an axis        by applying a suitable localized electric field, or by employing        piezoelectric actuation means. Once again, the mirrors are        matrix-addressable, such that addressed mirrors will reflect an        incoming radiation beam in a different direction to unaddressed        mirrors; in this manner, the reflected beam is patterned        according to the addressing pattern of the matrix-addressable        mirrors. The required matrix addressing can be performed using        suitable electronic means. In both of the situations described        hereabove, the patterning device can comprise one or more        programmable mirror arrays. More information on mirror arrays as        here referred to can be gleaned, for example, from U.S. Pat. No.        5,296,891 and U.S. Pat. No. 5,523,193, and PCT patent        applications WO 98/38597 and WO 98/33096, which are incorporated        herein by reference. In the case of a programmable mirror array,        the said support structure may be embodied as a frame or table,        for example, which may be fixed or movable as required; and    -   A programmable LCD array. An example of such a construction is        given in U.S. Pat. No. 5,229,872, which is incorporated herein        by reference. As above, the support structure in this case may        be embodied as a frame or table, for example, which may be fixed        or movable as required.

For purposes of simplicity, the rest of this text may, at certainlocations, specifically direct itself to examples involving a mask andmask table; however, the general principles discussed in such instancesshould be seen in the broader context of the patterning device ashereabove set forth.

Lithographic apparatus can be used, for example, in the manufacture ofintegrated circuits (ICs). In such a case, the patterning device maygenerate a circuit pattern corresponding to an individual layer of theIC, and this pattern can be imaged onto a target portion (e.g.comprising one or more dies) on a substrate (silicon wafer) that hasbeen coated with a layer of radiation-sensitive material (resist). Ingeneral, a single wafer will contain a whole network of adjacent targetportions that are successively irradiated via the projection system, oneat a time. In current apparatus, employing patterning by a mask on amask table, a distinction can be made between two different types ofmachine. In one type of lithographic apparatus, each target portion isirradiated by exposing the entire mask pattern onto the target portionat one time; such an apparatus is commonly referred to as a waferstepper or step-and-repeat apparatus. In an alternativeapparatus—commonly referred to as a step-and-scan apparatus—each targetportion is irradiated by progressively scanning the mask pattern underthe projection beam in a given reference direction (the “scanning”direction) while synchronously scanning the substrate table parallel oranti-parallel to this direction; since, in general, the projectionsystem will have a magnification factor M (generally<1), the speed V atwhich the substrate table is scanned will be a factor M times that atwhich the mask table is scanned. More information with regard tolithographic devices as here described can be gleaned, for example, fromU.S. Pat. No. 6,046,792, incorporated herein by reference.

In a manufacturing process using a lithographic apparatus, a pattern(e.g. in a mask) is imaged onto a substrate that is at least partiallycovered by a layer of radiation-sensitive material (resist). Prior tothis imaging step, the substrate may undergo various procedures, such aspriming, resist coating and a soft bake. After exposure, the substratemay be subjected to other procedures, such as a post-exposure bake(PEB), development, a hard bake and measurement/inspection of the imagedfeatures. This array of procedures is used as a basis to pattern anindividual layer of a device, e.g. an IC. Such a patterned layer maythen undergo various processes such as etching, ion-implantation(doping), metallization, oxidation, chemo-mechanical polishing, etc.,all intended to finish off an individual layer. If several layers arerequired, then the whole procedure, or a variant thereof, will have tobe repeated for each new layer. Eventually, an array of devices will bepresent on the substrate (wafer). These devices are then separated fromone another by a technique such as dicing or sawing, whence theindividual devices can be mounted on a carrier, connected to pins, etc.Further information regarding such processes can be obtained, forexample, from the book “Microchip Fabrication: A Practical Guide toSemiconductor Processing”, Third Edition, by Peter van Zant, McGraw HillPublishing Co., 1997, ISBN 0-07-067250-4, incorporated herein byreference.

For the sake of simplicity, the projection system may hereinafter bereferred to as the “lens”; however, this term should be broadlyinterpreted as encompassing various types of projection system,including refractive optics, reflective optics, and catadioptricsystems, for example. The radiation system may also include componentsoperating according to any of these design types for directing, shapingor controlling the projection beam of radiation, and such components mayalso be referred to below, collectively or singularly, as a “lens”.Further, the lithographic apparatus may be of a type having two or moresubstrate tables (and/or two or more mask tables). In such “multiplestage” devices the additional tables may be used in parallel, orpreparatory steps may be carried out on one or more tables while one ormore other tables are being used for exposures. Dual stage lithographicapparatus are described, for example, in U.S. Pat. No. 5,969,441 and PCTpatent application WO 98/40791, both incorporated herein by reference.

In a substrate processing system (an embodiment of which is sometimesknown as a lithography cell), typically comprising a lithographicapparatus and a track, multiple substrates (wafers) are processed. Suchsubstrates are processed in lots, each lot usually having up to 50substrates. At any one point in time, there may be a plurality of lotsin the substrate processing system. Furthermore, a recipe is associatedwith each lot, the recipe defining, among other things, the processsteps, equipment, material and timing applicable to the substrate(s) ofthe lot, such as the mask to be used, the resist type to be applied, theexposure dose, etc. So, with multiple lots in the substrate processingsystem, there may also be multiple recipes to be used in the substrateprocessing system. For example, at any one point in time, a substrateprocessing system can have between 30 and 50 substrates being processedin the system, which typically includes 4–6 lots. Continuing with thisexample, while several lots of the 4–6 lots may have the same recipe, anumber may have different recipes. In current substrate processingsystems, lots are processed in a first-come first-served manner, meaningthat each lot is processed in turn as it is provided to the substrateprocessing system, including changing any settings and/or configurations(hereinafter setup) of a part of the substrate processing system asneeded for the recipe of the first-come first-served lot.

A problem that has been identified is that when multiple lots areprocessed in a substrate processing system, a number of those lots maybe of a recipe type A and a number of those lots may be of recipe typeB, each recipe type requiring a specific substrate processing systemsetup. To change the setup from type A to type B often requires time inwhich the substrate processing system is typically not productive.Further, some substrate processing equipment, such as tracks, typicallyrun at the slowest rate of processing of the different types of lotspresent in the substrate processing system. In each circumstance,bottlenecks may develop which can slow down and even stop substrateprocessing. The result is that the rate and/or time of processing of anumber of substrate lots in the substrate processing system can benegatively impacted, which can lead to lower productivity of thesubstrate processing system. Thus, it would be advantageous to improvethe performance of processing of substrates in a substrate processingsystem.

SUMMARY

According to an aspect of the invention, there is provided a method forprocessing of substrates in at least a part of a substrate processingsystem, comprising:

-   obtaining, using a processing unit, at least one of a rate of    processing and a time of processing associated with a plurality of    substrate lots to be introduced into a part of the substrate    processing system; and-   determining, using the processing unit, an order of introduction of    the plurality of substrate lots into the part of the substrate    processing system to at least one of increase the rate of processing    and decrease the time of processing of the plurality of substrate    lots.

An increase of productivity of a substrate processing system can beachieved through appropriate ordering of substrate lots in the substrateprocessing system to increase the rate of processing and/or decrease thetime of processing of the lots in the substrate processing system.

According to a further aspect of the invention, there is provided acomputer program product for processing of substrates in at least a partof a substrate processing system, comprising:

-   software code configured to obtain at least one of a rate of    processing and a time of processing associated with a plurality of    substrate lots to be introduced into a part of the substrate    processing system; and-   software code configured to determine an order of introduction of    the plurality of substrate lots into the part of the substrate    processing system to at least one of increase the rate of processing    and decrease the time of processing of the plurality of substrate    lots.

According to a further aspect of the invention, there is provided alithographic apparatus comprising:

-   an illuminator configured to provide a projection beam of radiation;-   a support structure configured to hold a patterning device, the    patterning device configured to pattern the projection beam    according to a desired pattern;-   a substrate table configured to hold a substrate;-   a projection system configured to project the patterned beam onto a    target portion of the substrate; and-   a processing unit configured to obtain at least one of a rate of    processing and a time of processing associated with a plurality of    substrate lots to be introduced into a part of a substrate    processing system and to determine an order of introduction of the    plurality of substrate lots into the part of the substrate    processing system to at least one of increase the rate of processing    and decrease the time of processing of the plurality of substrate    lots.

According to a further aspect of the invention, there is provided atrack comprising:

-   a coater configured to apply a layer of radiation-sensitive material    to a substrate;-   a developer configured to develop an exposed substrate; and-   a processing unit configured to obtain at least one of a rate of    processing and a time of processing associated with a plurality of    substrate lots to be introduced into a part of a substrate    processing system and to determine an order of introduction of the    plurality of substrate lots into the part of the substrate    processing system to at least one of increase the rate of processing    and decrease the time of processing of the plurality of substrate    lots.

Although specific reference may be made in this text to the use of theapparatus according to the invention in the manufacture of ICs, itshould be explicitly understood that such an apparatus has many otherpossible applications. For example, it may be employed in themanufacture of integrated optical systems, guidance and detectionpatterns for magnetic domain memories, liquid-crystal display panels,thin-film magnetic heads, etc. The skilled artisan will appreciate that,in the context of such alternative applications, any use of the terms“reticle”, “wafer” or “die” in this text should be considered as beingreplaced by the more general terms “mask”, “substrate” and “targetportion”, respectively.

In the present document, the terms “radiation” and “beam” are used toencompass all types of electromagnetic radiation, including ultraviolet(UV) radiation (e.g. with a wavelength of 365, 248, 193, 157 or 126 nm)and extreme ultra-violet (EUV) radiation (e.g. having a wavelength inthe range 5–20 nm), as well as particle beams, such as ion beams orelectron beams.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying schematic drawings in whichcorresponding reference symbols indicate corresponding parts, and inwhich:

FIG. 1 depicts a lithographic apparatus according to an embodiment ofthe invention;

FIG. 2 depicts a schematic top view of a substrate processing systemcomprising a lithographic apparatus and a track according to anembodiment of the invention;

FIGS. 3 a and 3 b depict a schematic flow of substrates through asubstrate processing system according to an embodiment of the invention;and

FIGS. 4 a to 4 b depict flowcharts of evaluation and ordering of lots tobe introduced into a substrate processing system according toembodiments of the invention.

DETAILED DESCRIPTION

FIG. 1 schematically depicts a lithographic apparatus 9 according to aparticular embodiment of the invention. The apparatus comprises:

-   -   a radiation system IL, for supplying a projection beam PB of        radiation (e.g. EUV radiation). In this particular case, the        radiation system also comprises a radiation source LA;    -   a first object table (mask table) MT provided with a mask holder        for holding a mask MA (e.g. a reticle), and connected to first        positioning means PM for accurately positioning the mask with        respect to item PL;    -   a second object table (substrate table) WT provided with a        substrate holder for holding a substrate W (e.g. a resist-coated        silicon wafer), and connected to second positioning means PW for        accurately positioning the substrate with respect to item PL;        and    -   a projection system (“lens”) PL (e.g. a mirror system) for        imaging an irradiated portion of the mask MA onto a target        portion C (e.g. comprising one or more dies) of the substrate W.

As here depicted, the apparatus is of a reflective type (i.e. has areflective mask). However, in general, it may also be of a transmissivetype, for example (with a transmissive mask). Alternatively, theapparatus may employ another kind of patterning device, such as aprogrammable mirror array of a type as referred to above.

The source LA (e.g. a plasma source) produces a beam of radiation. Thisbeam is fed into an illumination system (illuminator) IL, eitherdirectly or after having traversed conditioning means, such as a beamexpander, for example. The illuminator IL may comprise adjusting meansfor setting the outer and/or inner radial extent (commonly referred toas σ-outer and σ-inner, respectively) of the intensity distribution inthe beam. In addition, it will generally comprise various othercomponents, such as an integrator and a condenser. In this way, the beamPB impinging on the mask MA has a desired uniformity and intensitydistribution in its cross-section.

It should be noted with regard to FIG. 1 that the source LA may bewithin the housing of the lithographic apparatus (as is often the casewhen the source LA is a mercury lamp, for example), but that it may alsobe remote from the lithographic apparatus, the radiation beam which itproduces being led into the apparatus (e.g. with the aid of suitabledirecting mirrors); this latter scenario is often the case when thesource LA is an excimer laser. The current invention and claimsencompass both of these scenarios.

The beam PB subsequently intercepts the mask MA, which is held on a masktable MT. Having been selectively reflected by the mask MA, the beam PBpasses through the projection system PL, which focuses the beam PB ontoa target portion C of the substrate W. With the aid of the secondpositioning means PW (and interferometric measuring means IF), thesubstrate table WT can be moved accurately, e.g. so as to positiondifferent target portions C in the path of the beam PB. Similarly, thefirst positioning means PM can be used to accurately position the maskMA with respect to the path of the beam PB, e.g. after mechanicalretrieval of the mask MA from a mask library, or during a scan. Ingeneral, movement of the object tables MT, WT will be realized with theaid of a long-stroke module (coarse positioning) and a short-strokemodule (fine positioning), which are not explicitly depicted in FIG. 1.However, in the case of a wafer stepper (as opposed to a step-and-scanapparatus) the mask table MT may just be connected to a short strokeactuator, or may be fixed. Mask MA and substrate W may be aligned usingmask alignment marks M1, M2 and substrate alignment marks P1, P2.

The depicted apparatus can be used in two different modes:

-   1. In step mode, the mask table MT is kept essentially stationary,    and an entire mask image is projected at one time (i.e. a single    “flash”) onto a target portion C. The substrate table WT is then    shifted in the x and/or y directions so that a different target    portion C can be irradiated by the beam PB; and-   2. In scan mode, essentially the same scenario applies, except that    a given target portion C is not exposed in a single “flash”.    Instead, the mask table MT is movable in a given direction (the    so-called “scan direction”, e.g. the y direction) with a speed ν, so    that the projection beam PB is caused to scan over a mask image;    concurrently, the substrate table WT is simultaneously moved in the    same or opposite direction at a speed V=Mv, in which M is the    magnification of the lens PL (typically, M=¼ or ⅕). In this manner,    a relatively large target portion C can be exposed, without having    to compromise on resolution.

FIG. 2 depicts a schematic view of the handling processes of a substrateW in a substrate processing system. The substrate processing system asshown in FIG. 2 comprises two main parts: the track 10 and thelithographic apparatus 9, as described, for example, with reference toFIG. 1. Substrates W can be moved from the track 10 to the lithographicapparatus 9 and vice versa through a substrate handler port 11, of whichtwo are shown in FIG. 2. The track 10 and the lithographic apparatus 9are also shown connected to each other by a communications channel 24and respectively to a processing unit 26. The communications channel 24facilitates transfer of information between the track 10 and thelithographic apparatus 9. In an embodiment, the communications channel24 also facilitates transfer of information between the processing unit26 and the track 10 and between the processing unit 26 and thelithographic apparatus 9. The processing unit 26 typically comprises amicroprocessor and appropriate software and will be described in moredetail below. The processing unit 26 is not required if the track 10and/or the lithographic apparatus 9 have a processing unit that canprovide the capabilities of the processing unit 26 as described in moredetail below. In an alternative, not shown in FIG. 2, the processingunit 26 may be unconnected to the lithographic apparatus 9 or the track10.

The substrates W are placed in track process stations, of which eightare shown in FIG. 2. Four of these process stations are coaters 12 andfour of these process stations are developers 14. In the coaters 12, thesubstrates W are coated with resist and in the developers 14 the exposedresist on the substrates are developed. Other processes can be carriedout at the coaters, developers or other process stations (not shown) aswill be known to a person skilled in the art.

The substrates W can be taken in and out of a process station 12,14 by afirst substrate handler 16 positioned in the track 10. As an example,the first substrate handler 16 can obtain a substrate W from a coater 12and then deliver the substrate W to a substrate handler port 11.Similarly, the first substrate handler 16 can obtain a substrate W froma substrate handler port 11 and then deliver the substrate W to adeveloper 14. The first substrate handler 16 can also take a substrate Wfrom a track input port 20 and deliver it to a process station 12, 14.Similarly, the first substrate handler 16 can also take a substrate Wfrom a process station 12, 14 and deliver it to a track output port 22.The track input port and track output port can be one and the same portor a plurality of ports. In an embodiment, the track input port and/orthe track output port can be a Front Opening Unified Pod (FOUP), whichis a container used to hold up to 25 substrates and which typicallycomprises a lot.

A second substrate handler 18, positioned in the lithographic apparatus9, transports a substrate W within the lithographic apparatus 9. As anexample, the second substrate handler 18 can obtain the substrate W froma substrate handler port 11 and then deliver the substrate W to apre-aligner 28 and/or to a substrate table WT. The pre-aligner 28 isused, for example, to accurately control the position of the substrate Wwith respect to the second substrate handler 18. A substrate table WT,of which two are shown in FIG. 2, can be positioned (for example, asindicated by the arrows), in order to move the substrate W during anexposure and/or alignment procedure. The second substrate handler 18 canalso obtain the substrate W from a substrate table WT and transport itto a substrate handler port 11.

In an embodiment, the processing unit has or has access to informationon the lots and types of lots to be introduced into a part of thesubstrate processing system. Such information can include details on theparticular recipe associated with a lot and the order of lots beingintroduced into the part of the substrate processing system. Asdescribed in more detail below, the processing unit can also determinethe order of lots to be introduced into the part of the substrateprocessing system. Further, the processing unit can provide informationabout the ordering of lots and lot recipes to be introduced into thepart of the substrate processing system to an operator and/or to adevice that controls introduction of the lots into the part of thesubstrate processing system. Optionally, the processing unit can controlthe order of introduction of lots into the part of the substrateprocessing system.

FIGS. 3 a and 3 b depict a schematic flow of substrates through asubstrate processing system according to an embodiment of the invention.One or more substrates comprising a single lot (although a plurality ofsubstrates can comprise more than one lot) are provided to track inputport 20 and flow towards coater 12 of the track 10. After the coater 12,the lot flows toward the lithographic apparatus 9 where the substrate(s)are exposed. After completion of exposure, the lot flows towards thedeveloper 14 and then out of the track 10 through track output port 22.After each lot is introduced into the substrate processing system,another lot can be introduced thereafter in effect resulting in a seriesof lots (and substrates) flowing through the substrate processing systemfor substrate processing.

In FIG. 3 a, an example of the effect of different lot types affectingthe flow of lots through a substrate processing system is shown. In thisexample, a plurality of the substrates of lot 1 of lot type A (lot typeA being represented by the dark shading) are in the track input port 20and one of the substrates of lot 1 of lot type A is in the coaters 12 ofthe track 10. Further, lots 2, 3, 4 and 5 of lot type B (lot type Bbeing represented by the light shading) are respectively in the coaters12 of the track, lithographic apparatus 9, the developers 14 of thetrack, and the track output port 22. As indicated by the arrows, thesubstrates of the various lots flow through the substrate processingsystem resulting in the movement of the lots through the substrateprocessing system. In this example, lot type A has a certain recipe,which defines a setup of the process steps, equipment, etc. for thesubstrates of the lot of that type and also establishes a rate forsubstrate processing of those substrates. Lot type B has another recipe,which defines a different setup of the process steps, equipment, etc.for the substrates of the lot of that type and also establishes adifferent rate for substrate processing of those substrates.

Due in part to the physical constraints of the track 10, the rate ofsubstrate processing in the track is typically limited to the lowestrate of substrate processing associated with a substrate in the track.Referring then to FIG. 3 a, the rate of substrate processing of track 10is limited to the lower of the substrate processing rates of lot type Aand lot type B since substrates from both lot types are in the track.So, even if lot type B has a higher rate of substrate processing thanlot type A, the rate of substrate processing in the track 10 is limitedto the rate associated with lot type A, although only one substrate oflot type A is in the track (i.e., one substrate of lot 1). The result isthat a slow lot will slow down the track from the moment it enters thetrack (slowing down previously started lots) until it leaves the track(slowing down lots started later).

In FIG. 3 b, another example of the effect of different lot typesaffecting the flow of lots through the substrate processing system isshown. In this example, lot 1 of lot type A (lot type A beingrepresented by the dark shading) is in the track input port 20. Lot 2 oflot type B (lot type B being represented by the light shading) is in thecoaters 12 of the track 10. Lot 3 of lot type A is in the lithographicapparatus 9. And, lots 4 and 5 of lot type B are respectively in thedevelopers 14 of the track and the track output port 22. As indicated bythe arrows, the substrates of the various lots flow through thesubstrate processing system resulting in the movement of the lotsthrough the substrate processing system. In this example, lot type A hasa certain recipe, which defines a setup of the process steps, equipment,etc. for the substrates of the lot of that type and also establishes arate for substrate processing of those substrates. Lot type B hasanother recipe, which defines a different setup of the process steps,equipment, etc. for the substrates of the lot of that type and alsoestablishes a different rate for substrate processing of thosesubstrates.

Changing the setup of process steps, equipment, etc. of all or a portionof a substrate processing system in accordance with a different recipecan take time. Referring then to FIG. 3 b, track 10 is set-up to handlesubstrates of lot type B (lots 2 and 4). However, as will be apparent,shortly substrates of lot type A (lot 1) will enter into the track 10from the track input port 20. Accordingly, a certain amount time will berequired to set-up at least part of the track 10, namely the coaters 12,to handle the substrates of lot type A. Similarly, substrates of lottype A (lot 3) will shortly enter into the track 10 from thelithographic apparatus 9, requiring a certain amount time to set-up atleast part of the track 10, namely the developers 14, to handle thesubstrates of lot type A. Furthermore, after lot 3 has passed throughthe developers 14, a certain amount of time will be required again tochange the setup of at least part of the track 10, namely the developers14, from those of lot type A to those of lot type B in order to handlelot 2 after it passes through the lithographic apparatus 9.

As can then be understood from FIGS. 3 a and 3 b, substrate processingin the substrate processing system can lose productivity due to thereduction of the substrate processing rate and/or delay resulting fromchanging the setup of all or part of the substrate processing system.Accordingly, it would be advantageous to order the introduction ofparticular lots into a part of the substrate processing system so as toreduce or eliminate such lost productivity. This could improve overallproductivity of the substrate processing system.

According to an embodiment of the invention, a plurality of substratelots to be introduced into a part of the substrate processing system areevaluated to determine whether it would be beneficial to change theorder in which the lots are introduced into, and thus processed in, thesubstrate processing system. In particular, the lot type of each of theplurality of lots could be evaluated to determine whether one or morelots of a certain lot type should be entered into a part of thesubstrate processing system in advance of one or more lots of anotherlot type. In addition or alternatively, that plurality of lots could beevaluated to determine whether one or more lots of a certain type can bebunched together, i.e., ordered consecutively. In each case, theevaluation can take into consideration reducing or eliminating thelowering of the substrate processing rate (or increasing of thesubstrate processing time) caused by the processing of substrates ofdifferent lot types in a part of the substrate processing system and/orreducing or eliminating the processing time resulting from changing thesetup of a part of the substrate processing system due to the processingof different lot types in the part of the substrate processing system.In accordance with the evaluation, an appropriate order of the pluralityof lots can be applied to the plurality of lots in the queue of lots tobe introduced to the part of the substrate processing system.

More specifically, a rate of processing and/or a time of processingassociated with a plurality of substrate lots to be introduced into apart of the substrate processing system can be obtained (e.g.,calculated, read from a table, requested from a database or a part ofthe substrate processing system, etc.). With such information, an orderof introduction of the plurality of substrate lots into the part of thesubstrate processing system can be determined to increase the rate ofprocessing and/or decrease the time of processing of the plurality ofsubstrate lots. The order of introduction can be then supplied to, forexample, a host computer for the substrate processing system, a part ofthe substrate processing system (such as the track and/or lithographicapparatus), a device that interacts with the substrate processing system(e.g., a device that delivers lots to and/or stores lots for thesubstrate processing system such as a FOUP handler) or a user so thatthe order of introduction can be applied to the lots to be introducedinto the part of the substrate processing system.

So, in an implementation, a processing unit can determine per lot typeof a plurality of lots in a queue of lots to be introduced into a partof the substrate processing system what changes in setup, if any, arerequired in that or other parts of the substrate processing system tohandle another lot type of the plurality of lots. The time of processingassociated with changing a setup of a part of the substrate processingsystem handling one lot type of the plurality of lots to handle anotherlot type of the plurality of lots (and hence associated with theplurality of lots generally) is obtained. With the processing times, anorder of the introduction of lots into the substrate processing systemwith the least (or at least lower) processing time due to setup changescan be derived and then applied. Consider an example lot queue thatcomprises 4 lots of 3 different lot types: lot 1—type A, lot 2—type B,lot 3—type A, and lot 4—type C. Since lots 1 and 3 are of the same lottype (lot type A), they would have the same setup. Hence, re-orderingthe 4 lots in the queue into the order lot 1, lot 3, lot 2 and lot 4could result in less time lost to changing of the setup of the substrateprocessing system. Similar time savings can be realized by consecutivelyordering lot types that share one or more of the same setup settingsand/or configurations.

In an example application of this implementation, the processing unitcan evaluate a plurality of lots to be introduced into the substrateprocessing system to determine the different recipes in the plurality oflots. Then for each of the different recipes, the processing unit candetermine from the recipe what changes in setup, if any, are requiredfor the lithographic apparatus of the substrate processing system (e.g.,mask, annular/dipole/quadrupole illumination, illumination settings,etc.) and/or what changes in setup, if any, are required for the trackof the substrate processing system (e.g., bake plate temperature, coatermodules required, resist types, etc.) to handle another recipe of theplurality of lots. The processing unit can then apply a model to obtainthe processing times, associated with these changes, caused by thevarious transitions from one recipe to another recipe. The informationin the model used to obtain these times of processing can be, forexample, pre-programmed in the processing unit and/or supplied by thelithographic apparatus and/or the track. Further, the model can be, forexample, a simple look-up engine of pre-determined processing timesassociated with recipe transitions or a calculator that combines recipeinformation with track and/or lithographic apparatus parameters,settings, etc. to calculate the processing time of recipe transitions.

With the obtained processing times of the recipe transitions, an ordercan be determined by selecting the order of the plurality of lots havingthe lowest processing time (or at least a lower processing time thanbefore re-ordering), which can be determined by selecting the lowestprocessing time (or at least a lower processing time than beforere-ordering) of the processing times for all the order permutations ofthe plurality of lots. For example, consider a lot queue that comprises4 lots of 3 different lot types: lot 1—type A, lot 2—type B, lot 3—typeA, and lot 4—type C. The overall processing time associated with therecipe transitions is calculated: for the order lot 1—type A, lot 2—typeB, lot 3—type A, and lot 4—type C; for the order lot 1—type A, lot2—type B, lot 4—type C, and lot 3'type A; for the order lot 1—type A,lot 3—type A, lot 2—type B, and lot 4—type C; etc.—that is, for eachpermutation of lot order for the 4 lots (24 permutations). The lot orderthen selected is the lot order associated with the lowest overallprocessing time (or at least a lower processing time than the processingtime before re-ordering) of those calculated processing times.

In another implementation, a processing unit can obtain the time and/orrate of processing through all or part of the substrate processingsystem for each lot type of a plurality of lots in the queue of lots tobe introduced into the substrate processing system. The rate ofprocessing can comprise a throughput value, e.g., number of substratesper hour. The time of processing can comprise a cycle time, e.g., numberof seconds to process a lot. Having the information on these timesand/or rates of processing associated with the plurality of lots, theplurality of lots in the queue can be ordered to increase the overallrate of processing of the plurality of lots in the queue and/or toreduce the overall time of processing of the plurality of lots in thequeue (compared to the rate and/or time of processing of the pluralityof lots before re-ordering). In a first variant, the ordering cancomprise sorting the plurality of lots in the queue, for example, sothat the difference between throughput value or cycle times betweenconsecutive lots is reduced. For example, consider lot types that have 3different rates of processing—Fast (F), Medium (M) and Slow (S). A lotqueue may comprise 5 lots in the following order: F-S-F-S-M. These lotswill all run at an average rate of processing close to the slowest lotS. By sorting the lots to either F-F-M-S-S or S-S-M-F-F the average rateof each lot is much closer to its theoretical rate. In a second variant,the ordering can comprise selecting the order of the plurality of lotshaving the lowest overall processing time or rate (or at least a lowerprocessing time or rate than the processing time or rate beforere-ordering), which can be determined by selecting the lowest processingtime or rate (or at least a lower processing time or rate than theprocessing time or rate before re-ordering) of the processing times orrates for all the order permutations of the plurality of lots. Forexample, consider a lot queue comprising 5 lots in the following order:1-2-3-4-5. According to this variant, the overall processing time orrate is obtained for lot order 1-2-3-4-5, for lot order 1-2-3-5-4, forlot order 1-2-4-3-5, etc.—that is, for each permutation of lot order forthe 5 lots (120 permutations). The lot order then selected is the lotorder associated with the lowest processing time or rate (or at least alower processing time or rate than the processing time or rate beforere-ordering) of those modeled processing times or rates.

In an example application of this implementation, the processing unitcan evaluate a plurality of lots to be introduced into the substrateprocessing system to determine the different recipes in the plurality oflots. For each of the different recipes, the processing unit can obtain,from the recipe and lithographic apparatus and/or track setup, the rateof processing and/or the time of processing for each recipe through thetrack and/or lithographic apparatus of the substrate processing system.As an example, knowing the number of modules in the track and/orlithographic apparatus used according to the recipe, the process time ofeach module and the number of process steps, the processing unit canapply a model to calculate a maximum throughput value or a minimum cycletime for each recipe. The information used to obtain the rate and/ortime of processing can be, for example, pre-programmed in the processingunit and/or supplied by the lithographic apparatus and/or the track.Further, the processing unit can have, for example, a simple look-upengine of pre-determined processing times or rates associated with flowof a recipe through the track and/or lithographic apparatus or acalculator that combines recipe information with track and/orlithographic apparatus parameters, settings, etc. to calculate theprocessing times and/or rates.

With the obtained processing times and/or rates, an appropriate order oflots can be determined. For example, the order of lots can be determinedby sorting the order of lots by the rate or time of processing or byselecting the order of the plurality of lots having the lowestprocessing time or rate (or at least a lower processing time or ratethan before re-ordering), which can be determined by selecting thelowest processing time or rate (or at least a lower processing time orrate than before re-ordering) of the processing times or rates for allthe order permutations of the plurality of lots.

FIGS. 4 a and 4 b depict flowcharts of these respective implementationsof an embodiment of the invention. Further, these implementations may becombined together. A result of such a combination could be a morecomprehensive order of the lots to provide improved processing ofsubstrates in the substrate processing system. For example, a processingunit can obtain per lot type of a plurality of lots in a queue of lotsto be introduced into a part of the substrate processing system the timeand/or rate of processing associated with the processing of that lottype through all or part of the substrate processing system andassociated with changes in substrate processing system setup that arerequired to handle another lot type of the plurality of lots. With theobtained processing times and/or rates, an appropriate order of lots canbe determined. For example, the order of lots can be determined byselecting the order of the plurality of lots having the lowestprocessing time or rate (or at least a lower processing time or ratethan before re-ordering), which can be determined by selecting thelowest processing time or rate (or at least a lower processing time orrate than before re-ordering) of the processing times or rates for allthe order permutations of the plurality of lots. In this case, theprocessing times or rates include the times and rates attributed toprocessing the lot type through all or part of the substrate processingsystem and attributed to changes in substrate processing system setupthat are required to handle another lot type of the plurality of lots.

Further, it should be noted that in some cases rates and/or times ofprocessing per lot type/recipe may not be uniform among all lots havingthe same lot type/recipe. For example, activities specific to aparticular substrate of a lot may apply such as a metrology activity. Inthat case, the rate or time of processing cannot apply to all lots ofthe same type/recipe due to such per substrate variances in certainlots. Accordingly, in an extension of the above-described embodimentsand implementations, such per substrate activities may be accounted forin the determination of lot order. Similarly, certain pre-conditionsand/or post-conditions can affect the ordering of lots. Supply ofmaterials to or performance of actions in a part of the substrateprocessing system, for instance, may impact an otherwise appropriate lotorder. For example, substrates of a lot may not be ready forintroduction into the part of the substrate processing system,processing materials (e.g. a resist) may not have been supplied to apart of the substrate processing system, a calibration or other test maynot have been performed, etc., all of which can cause slowing ofprocessing of lots. Accordingly, in an extension of the above-describedembodiments and implementations, pre-conditions and/or post-conditionsmay be accounted for in the determination of the lot order.

According to an embodiment, the processing unit may comprise a softwarescheduler to order and schedule the introduction of lots into a part ofthe substrate processing system. With information about the possiblelots that can be introduced into a part of the substrate processingsystem (i.e., lots in the queue), a plurality of lots can be ordered andscheduled through the scheduler to be introduced into the part of thesubstrate processing system so as to improve the overall rate and/ortime of processing of those lots.

In this embodiment, the scheduler has or receives information about thelots that can be introduced into the part of the substrate processingsystem. For example, the scheduler may have or receive informationregarding lots that can be introduced into the substrate processingsystem, i.e., that are in the queue. Such lot queue information caninclude information about the number and identity of lots that can beintroduced into the substrate processing system, the types of those lotsand/or recipe associated with each lot, the number of substrates in eachlot, etc. The scheduler further may have or receive information aboutthe processing of lots in the substrate processing system. Such lotprocessing information can include information about the setup of one ormore parts of the substrate processing system (e.g., mask,annular/dipole/quadrupole illumination, and/or illumination settings ofthe lithographic apparatus, bake plate temperature, coater modulesrequired and resist types of the track, etc.), data about the currentstatus of substrate processing in a part of the substrate processingsystem, processing rates or times associated with modules in a part ofthe substrate processing system, etc. Such lot queue and/or lotprocessing information may be, for instance, provided by a host computerfor the substrate processing system, provided by a part of the substrateprocessing system (such as the track and/or lithographic apparatus),provided by a device that interacts with the substrate processing system(e.g., a device that delivers lots to and/or stores lots for thesubstrate processing system such as a FOUP handler) or provided by auser.

With all the necessary information, the scheduler can determine anappropriate lot order as described in the above embodiments,implementations and/or their combinations. Of course, any otherappropriate ordering algorithm may be applied to order the lots.

Once the lot order has been determined, the scheduler can schedule theintroduction of lots into a part of the substrate processing system,such as the track or lithographic apparatus. For example, the order ofintroduction can be supplied to a host computer for the substrateprocessing system, a part of the substrate processing system (such asthe track and/or lithographic apparatus), a device that interacts withthe substrate processing system (e.g., a device that delivers lots toand/or stores lots for the substrate processing system such as a FOUPhandler) or a user so that the order of introduction can be applied tothe lots to be introduced into the part of the substrate processingsystem. In an implementation, one or more parts of the substrateprocessing system and/or a device that interacts with the substrateprocessing system allows the scheduler to activate the introduction oflots into the substrate processing system.

As noted earlier, the processing unit 26 typically comprises amicroprocessor and appropriate software. The processing unit 26 is notrequired if the track 10 and/or the lithographic apparatus 9 have aprocessing unit that can provide the capabilities of the processing unit26. Processing unit 26 will usually comprises software to perform themethods described above. As noted above, processing unit 26 may bestand-alone. Moreover, processing unit 26 may comprises multiplemicroprocessors and/or modules of software distributed on varioussubstrate processing equipment or other devices. Similarly, thescheduler may implemented in a stand-alone manner, as part of the trackand/or lithographic apparatus of the substrate processing system, inmultiple modules distributed on various substrate processing equipmentor other devices, etc.

More generally, each step of the method may be executed on any generalcomputer, such as a mainframe computer, personal computer or the likeand pursuant to one or more, or a part of one or more, program modulesor objects generated from any programming language, such as C++, Java,Fortran or the like. And still further, each step, or a file or objector the like implementing each step, may be executed by special purposehardware or a circuit module designed for that purpose. For example, theinvention may be implemented as a firmware program loaded intonon-volatile storage or a software program loaded from or into a datastorage medium as machine-readable code, such code being instructionsexecutable by an array of logic elements such as a microprocessor orother digital signal processing unit.

The invention may be implemented as an article of manufacture comprisinga computer usable medium having computer readable program code meanstherein for executing the method steps of the invention, a programstorage device readable by a machine, tangibly embodying a program ofinstructions executable by a machine to perform the method steps of theinvention, a computer program product, or an article of manufacturecomprising a computer usable medium having computer readable programcode means therein, the computer readable program code means in saidcomputer program product comprising computer readable code means forcausing a computer to execute the steps of the invention. Such anarticle of manufacture, program storage device, or computer programproduct may include, but is not limited to, CD-ROMs, diskettes, tapes,hard drives, computer system memory (e.g. RAM or ROM) and/or theelectronic, magnetic, optical, biological or other similar embodiment ofthe program (including, but not limited to, a carrier wave modulated, orotherwise manipulated, to convey instructions that can be read,demodulated/decoded and executed by a computer). Indeed, the article ofmanufacture, program storage device or computer program product mayinclude any solid or fluid transmission medium, magnetic or optical, orthe like, for storing or transmitting signals readable by a machine forcontrolling the operation of a general or special purpose computeraccording to the method of the invention and/or to structure itscomponents in accordance with a system of the invention.

The invention may also be implemented in a system. A system may comprisea computer that includes a processor and a memory device and optionally,a storage device, an output device such as a video display and/or aninput device such as a keyboard or computer mouse. Moreover, a systemmay comprise an interconnected network of computers. Computers mayequally be in stand-alone form (such as the traditional desktop personalcomputer) or integrated into another apparatus (such a cellulartelephone).

The system may be specially constructed for the required purposes toperform, for example, the method steps of the invention or it maycomprise one or more general purpose computers as selectively activatedor reconfigured by a computer program in accordance with the teachingsherein stored in the computer(s). The system could also be implementedin whole or in part as a hard-wired circuit or as a circuitconfiguration fabricated into an application-specific integratedcircuit. The invention presented herein is not inherently related to aparticular computer system or other apparatus. The required structurefor a variety of these systems will appear from the description given.

In the case of diagrams depicted herein, they are provided by way ofexample. There may be variations to these diagrams or the steps (oroperations) described herein without departing from the spirit of theinvention. For instance, in certain cases, the steps may be performed indiffering order, or steps may be added, deleted or modified. All ofthese variations are considered to comprise part of the presentinvention as recited in the appended claims.

While specific embodiments of the invention have been described above,it will be appreciated that the invention may be practiced otherwisethan as described. The description is not intended to limit theinvention.

1. A computer program product for processing of substrates in at least a part of a substrate processing system, comprising: software code configured to obtain at least one of a rate of processing and a time of processing associated with a plurality of substrate lots to be introduced into a part of the substrate processing system; and software code configured to determine an order of introduction of the plurality of substrate lots into the part of the substrate processing system to at least one of increase the rate of processing and decrease the time of processing of the plurality of substrate lots.
 2. The computer program product according to claim 1, wherein said code configured to obtain at least one of the rate of processing and the time of processing comprises code configured to obtain, for each lot type of the plurality of lots, the time of processing required to change a setup of a part of the substrate processing system handling that lot type to handle each of one or more other lot types of the plurality of lots.
 3. The computer program product according to claim 1, wherein said code configured to determine an order comprises code configured to determine an order of the plurality of lots with the least processing time to change a setup of a part of the substrate processing system for the plurality of lots.
 4. The computer program product according to claim 1, wherein said code configured to obtain at least one of the rate of processing and the time of processing comprises code configured to obtain at least one of the rate of processing and the time of processing of each lot type of the plurality of lots through a part of the substrate processing system.
 5. The computer program product according to claim 1, wherein said code configured to determine an order comprises code configured to sort the order of the plurality of lots so that the difference between the at least one of rate of processing and time of processing of consecutive lots is reduced.
 6. The computer program product according to claim 1, wherein said code configured to determine an order comprises code configured to select the order of the plurality of lots having the lowest overall processing time or rate of the processing times or rates for all the order permutations of the plurality of lots.
 7. The computer program product according to claim 1, wherein: said code configured to obtain at least one of the rate of processing and the time of processing comprises code configured to obtain, for each lot type of the plurality of lots, the time of processing required to change a setup of a part of the substrate processing system handling that lot type to handle each of one or more other lot types of the plurality of lots and to obtain at least one of the rate of processing and time of processing of each lot type of the plurality of lots through a part of the substrate processing system; and said code configured to determine an order comprises code configured to select the order of the plurality of lots having the lowest overall processing time or rate of the processing times or rates for all the order permutations of the plurality of lots.
 8. The computer program product according to claim 1, wherein said code configured to obtain at least one of the rate of processing and the time of processing comprises code configured to calculate the at least one of the rate of processing and time of processing using a recipe associated with one or more lots of the plurality of lots and using setup information regarding the part of the substrate processing system.
 9. The computer program product according to claim 1, wherein said substrate processing system comprises a lithographic apparatus and a track.
 10. The computer program product according to claim 1, wherein said computer program product is operated externally from a lithographic apparatus and a track.
 11. The computer program product according to claim 1, further comprising code configured to schedule the introduction of the plurality of lots into the part of the substrate processing system according to the order.
 12. A method for processing of substrates in at least a part of a substrate processing system, comprising: obtaining, using a processing unit, at least one of a rate of processing and a time of processing associated with a plurality of substrate lots to be introduced into a part of the substrate processing system; and determining, using the processing unit, an order of introduction of the plurality of substrate lots into the part of the substrate processing system to at least one of increase the rate of processing and decrease the time of processing of the plurality of substrate lots.
 13. The method according to claim 12, wherein said obtaining comprises obtaining, for each lot type of the plurality of lots, the time of processing required to change a setup of a part of the substrate processing system handling that lot type to handle each of one or more other lot types of the plurality of lots.
 14. The method according to claim 12, wherein said determining an order comprises determining an order of the plurality of lots with the least processing time to change a setup of a part of the substrate processing system for the plurality of lots.
 15. The method according to claim 12, wherein said obtaining comprises obtaining at least one of the rate of processing and the time of processing of each lot type of the plurality of lots through a part of the substrate processing system.
 16. The method according to claim 12, wherein said determining an order comprises sorting the order of the plurality of lots so that the difference between the at least one of rate of processing and time of processing of consecutive lots is reduced.
 17. The method according to claim 12, wherein said determining an order comprises selecting the order of the plurality of lots having the lowest overall processing time or rate of the processing times or rates for all the order permutations of the plurality of lots.
 18. The method according to claim 12, wherein: said obtaining comprises obtaining, for each lot type of the plurality of lots, the time of processing required to change a setup of a part of the substrate processing system handling that lot type to handle each of one or more other lot types of the plurality of lots and obtaining at least one of the rate of processing and time of processing of each lot type of the plurality of lots through a part of the substrate processing system; and said determining an order comprises selecting the order of the plurality of lots having the lowest overall processing time or rate of the processing times or rates for all the order permutations of the plurality of lots.
 19. The method according to claim 12, wherein said substrate processing system comprises a lithographic apparatus and a track.
 20. The method according to claim 12, wherein said obtaining comprises calculating the at least one of the rate of processing and time of processing using a recipe associated with one or more lots of the plurality of lots and using setup information regarding the part of the substrate processing system.
 21. A lithographic apparatus comprising: an illuminator configured to condition a beam of radiation; a support structure configured to hold a patterning device, the patterning device configured to pattern the beam according to a desired pattern; a substrate table configured to hold a substrate; a projection system configured to project the patterned beam onto a target portion of the substrate; and a processing unit configured to obtain at least one of a rate of processing and a time of processing associated with a plurality of substrate lots to be introduced into a part of a substrate processing system and to determine an order of introduction of the plurality of substrate lots into the part of the substrate processing system to at least one of increase the rate of processing and decrease the time of processing of the plurality of substrate lots.
 22. The lithographic apparatus according to claim 21, wherein the processing unit is configured to calculate the at least one of the rate of processing and time of processing using a recipe associated with one or more lots of the plurality of lots and using setup information regarding the lithographic apparatus.
 23. The lithographic apparatus according to claim 21, wherein: the processing unit is configured to obtain, for each lot type of the plurality of lots, the time of processing required to change a setup of a part of the substrate processing system handling that lot type to handle each of one or more other lot types of the plurality of lots and to obtain at least one of the rate of processing and time of processing of each lot type of the plurality of lots through a part of the substrate processing system; and the processing unit is configured to select the order of the plurality of lots having the lowest overall processing time or rate of the processing times or rates for all the order permutations of the plurality of lots.
 24. A track comprising: a coater configured to apply a layer of radiation-sensitive material to a substrate; a developer configured to develop an exposed substrate; and a processing unit configured to obtain at least one of a rate of processing and a time of processing associated with a plurality of substrate lots to be introduced into a part of a substrate processing system and to determine an order of introduction of the plurality of substrate lots into the part of the substrate processing system to at least one of increase the rate of processing and decrease the time of processing of the plurality of substrate lots.
 25. The track according to claim 24, wherein the processing unit is configured to calculate the at least one of the rate of processing and time of processing using a recipe associated with one or more lots of the plurality of lots and using setup information regarding the track.
 26. The track according to claim 24, wherein: the processing unit is configured to obtain, for each lot type of the plurality of lots, the time of processing required to change a setup of a part of the substrate processing system handling that lot type to handle each of one or more other lot types of the plurality of lots and to obtain at least one of the rate of processing and time of processing of each lot type of the plurality of lots through a part of the substrate processing system; and the processing unit is configured to select the order of the plurality of lots having the lowest overall processing time or rate of the processing times or rates for all the order permutations of the plurality of lots. 